1. Field of the Invention
The present invention relates to wrenches and more particularly to an improved wrench having a ratchet wheel arrangement in its enclosed box portion.
2. Description of Related Art
A variety of wrenches are commercially available. A prior wrench is shown in FIG. 1 and comprises an enclosed box portion 1 including a circular opening 2 and a crescent cavity 3 adjacent its handle and being in communication with the opening 2, a ratchet wheel 4 having a central opening, the ratchet wheel 4 being fitted in the opening 2, a pawl 5 in the cavity 3, a slanted receptacle 6 recessed at the cavity 3, a spring 7 having one end anchored in the receptacle 6 and the other end anchored at the pawl 5 for resiliently urging the pawl 5 against the ratchet wheel 4 for engagement. The prior art has the drawbacks of being difficult of manufacturing and having reduced number of teeth engaged between the pawl 5 and the ratchet wheel 4, resulting in a significant reduction of exerted force on a thing to be fastened or unfastened.
Another prior wrench is shown in FIG. 2 and comprises an enclosed box portion 8 including a circular opening 9, a ratchet wheel 10 having a central opening, the ratchet wheel 10 being fitted in the opening 9, a channel 11 open to both the external and the ratchet wheel 10, a pawl 12 at an inner end of the channel 11, a cap 14 threadedly secured to an outer end of the channel 11, and a spring 13 biased between the pawl 12 and the cap 14 for resiliently urging the pawl 12 against the ratchet wheel 10 for engagement. The prior art still has the drawback of having reduced number of teeth engaged between the pawl 12 and the ratchet wheel 10, resulting in a significant reduction of exerted force on a thing to be fastened or unfastened. Thus, the need for improvement still exists.